Page 443 - Schaum's Outline of Theory and Problems of Applied Physics

428 ATOMIC PHYSICS [CHAP. 34

34.16. The kinetic energy of a neutron (mass 1.675 × 10 −22 kg) whose de Broglie wavelength is 2.0 × 10 −14 mis
(a) 3.3 × 10 −13 eV (c) 2.0 MeV
(b) 0.21 eV (d) 0.37 GeV

Supplementary Problems

34.1. Why is the uncertainty principle only significant for such extremely small particles as electrons and protons even
though it applies to objects of all sizes?

34.2. What relationship would you expect between the chemical activity of a metal and its ionization energy?
34.3. What is the nature of the spectrum found in (a) light from the hot filament of a light bulb, (b) light from a neon sign,
and (c) light originating as in (a) that has passed through cool neon gas.
34.4. How are the compositions of the sun and stars determined?

34.5. Why does the spectrum of hydrogen consist of many lines even though a hydrogen atom has only a single electron?

34.6. In the Bohr model of the hydrogen atom, what condition must be obeyed by the electron if it is to move in its orbit
indefinitely without radiating energy?

34.7. What is the chief way in which light from a laser differs from light from other sources?

34.8. Find the de Broglie wavelength of a 10-g rifle bullet traveling at the velocity of sound, 331 m/s.
34.9. Find the kinetic energy in eV of an electron whose de Broglie wavelength is 10 −10 m.

34.10. An experiment is planned in which the momentum of an electron is to be measured to within ±10 −20 kg·m/s while
its position is known to within ±10 −10 m. Do you think the experiment will succeed?
34.11. A proton is confined to a region 10 −9 m across. (a) Find the uncertainty in its momentum. (b) Find the minimum
energy it can have.

34.12. The earth’s mass is 6 × 10 24 kg, the radius of its orbit around the sun is 1.5 × 10 11 m, and its orbital velocity is
4
3 × 10 m/s. (a) Find the de Broglie wavelength of the earth. (b) Find the quantum number of the earth’s orbit.
(c) Do you think quantum considerations play an important part in the earth’s orbital motion?
34.13. How much energy is needed to remove the electron from a hydrogen atom when it is in the n = 4 state?

34.14. How does the average energy per molecule in a gas at 20 C compare with the energy needed to raise a hydrogen
◦
atom from its ground state to its lowest excited state?
34.15. Find the velocity of the electron in the n = 5 state of a hydrogen atom according to the Bohr model. Is this more or
less than the velocity of the electron when it is in the n = 1 state?

34.16. What m l values are possible for an electron in a state of n = 4, l = 3?

34.17. How many electrons are there in a closed l = 3 subshell?
34.18. What is the effective nuclear charge that acts on each electron in the outer shell of the calcium (Z = 20) atom? Would
you think that such an electron is relatively easy or relatively hard to detach from the atom?

34.19. What is the effective nuclear charge that acts on each electron in the outer shell of the sulfur (Z = 16) atom? Would
you think that such an electron is relatively easy or relatively hard to detach from the atom?